Neves Raquel A F, Fernandes Tainá, Santos Luciano Neves Dos, Nascimento Silvia M
Laboratório de Microalgas Marinhas, Departamento de Ecologia e Recursos Marinhos, Instituto de Biociências, Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil.
Laboratório de Ictiologia Teórica e Aplicada, Departamento de Ecologia e Recursos Marinhos, Instituto de Biociências, Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil.
PLoS One. 2017 Apr 7;12(4):e0175168. doi: 10.1371/journal.pone.0175168. eCollection 2017.
Harmful algae may differently affect their primary grazers, causing sub-lethal effects and/or leading to their death. The present study aim to compare the effects of three toxic benthic dinoflagellates on clearance and grazing rates, behavioral changes, and survival of Artemia salina. Feeding assays consisted in 1-h incubations of brine shrimps with the toxic Prorocentrum lima, Gambierdiscus excentricus and Ostreopsis cf. ovata and the non-toxic Tetraselmis sp. Brine shrimps fed unselectively on all toxic and non-toxic algal preys, without significant differences in clearance and ingestion rates. Acute toxicity assays were performed with dinoflagellate cells in two growth phases during 7-h to assess differences in cell toxicity to A. salina. Additionally, exposure to cell-free medium was performed to evaluate its effects on A. salina survival. The behavior of brine shrimps significantly changed during exposure to the toxic dinoflagellates, becoming immobile at the bottom by the end of the trials. Dinoflagellates significantly affected A. salina survival with 100% mortality after 7-h exposure to cells in exponential phase (all treatments) and to P. lima in stationary phase. Mortality rates of brine shrimps exposed to O. cf. ovata and G. excentricus in stationary phase were 91% and 75%, respectively. However, incubations of the brine shrimps with cell-free medium did not affect A. salina survivorship. Significant differences in toxic effects between cell growth phases were only found in the survival rates of A. salina exposed to G. excentricus. Acute exposure to benthic toxic dinoflagellates induced harmful effects on behavior and survival of A. salina. Negative effects related to the toxicity of benthic dinoflagellates are thus expected on their primary grazers making them more vulnerable to predation and vectors of toxins through the marine food webs.
有害藻类可能会对其主要食草动物产生不同影响，造成亚致死效应和/或导致其死亡。本研究旨在比较三种有毒底栖甲藻对卤虫清除率和摄食率、行为变化及存活情况的影响。摄食试验包括将卤虫与有毒的利马原甲藻、偏心膝沟藻和卵形奥氏藻以及无毒的四爿藻进行1小时的共培养。卤虫对所有有毒和无毒藻类猎物均无选择性摄食，清除率和摄食率无显著差异。在两个生长阶段用甲藻细胞进行7小时的急性毒性试验，以评估细胞对卤虫的毒性差异。此外，让卤虫接触无细胞培养基以评估其对卤虫存活的影响。在接触有毒甲藻期间，卤虫的行为发生了显著变化，试验结束时在底部静止不动。甲藻显著影响卤虫的存活，在指数生长期（所有处理）接触细胞7小时后以及在静止期接触利马原甲藻后，死亡率达100%。在静止期接触卵形奥氏藻和偏心膝沟藻的卤虫死亡率分别为91%和75%。然而，将卤虫与无细胞培养基共培养并未影响卤虫的存活率。仅在接触偏心膝沟藻的卤虫存活率方面发现细胞生长阶段之间存在显著的毒性效应差异。急性接触底栖有毒甲藻会对卤虫的行为和存活产生有害影响。因此，预计底栖甲藻的毒性会对其主要食草动物产生负面影响，使它们更容易通过海洋食物网被捕食并成为毒素载体。
